Most people assume that the central bank prints money when it buys bonds. They further assume that this increase in the quantity of money causes an increase in the general price level. And, this leads them to assume that the value of the money is 1 / P (P is the general price level). Therefore, when the central bank prints money to buy bonds, it is diluting the value of the money held by everyone—in proportion to the amount printed divided by the total amount in circulation.
This is not even wrong. So let’s look at how it really works.
Of course, as we’ve said many times before, the dollar is not money. It is irredeemable credit. And so is the Treasury bond. The difference between the currency and the bond is maturity. The currency is credit of zero duration and the bond has a duration of e.g. 10 years.
The Fed is not printing, but merely exchanging one irredeemable credit for another.